CFP & CFP2 Coherent Transceiver
Coherent Optics is a high performance CFP transceiver module based on DP-QPSK modulation for 100 Gigabit data links over two single mode fibres.
The maximum reach is beyond 2000km without inline chromatic dispersion compensation.
The amplified narrow linewidth tunable laser is shared between the transmitter and receiver sections.
A Tunable Optical Filter (TOF) reduces the Amplified Spontaneous Emission (ASE) created by the EDFA.
A tapped monitor diode is used to control the optical output power.
https://blog.skylaneoptics.com/what-is-coherent-optics/